Process for preparation of aqueous suspensions of mineral loads, aqueous suspensions of mineral loads obtained and their uses

ABSTRACT

The invention concerns a process for the preparation of aqueous suspensions of fluid mineral matter, which are able to be pumped and conveyed by the end user  5  immediately after the filtration stage, possibly followed by a compression, which process comprises filtration in two separate stages. 
     The invention also concerns aqueous suspensions of mineral matter obtained and their uses.

FIELD OF THE INVENTION

The present invention concerns the technical sector of mineral loads,such as notably the paper production field and in particular papercoating and mass-loading of paper, or the fields of paint, watertreatment such as notably the field of purification muds, detergency,ceramics, cements or hydraulic binders, public works, inks and 10varnishes, gluing of textiles or any type of industry requiring the useof concentrated pigment suspensions, and concerns more particularly thefields of paper, water treatment, paint and ceramics.

In a more particular manner, the invention concerns a process forpreparation of aqueous suspensions of mineral loads or pigments with asatisfactory rheology used in the various abovementioned fields.

BACKGROUND OF THE INVENTION

To accomplish the industrial applications in the above fields, it isnecessary to produce suspensions of mineral loads, notably calciumcarbonates, with an excellent rheology, i.e. with a low viscosity duringthe period of storage to facilitate manipulating and application ofthem, and as high as possible a mineral matter content, in order toreduce the quantity of water handled.

During production of these aqueous suspensions of mineral loadssatisfying the abovementioned criteria, some processes lead to weaklyconcentrated aqueous suspensions of mineral or organic matter.

These suspensions must then be concentrated to offer them to the enduser who use the aqueous suspensions or to eliminate the solventspresent when these loads are used in a powder form.

One of the means known currently is to concentrate these suspensions bya filtration process, but these filtrations have until the present dayled to cakes which are so compact that it is necessary firstly to addthe dispersant after the filtration stage and secondly to use a highmechanical energy to return them to suspension or convey theconcentrated suspensions.

Thus, patent application WO 00/39029 teaches those skilled in the artthat a process to prepare an aqueous suspension of calcium carbonateconsists in following the filtration stage with a thermal concentrationstage and then with a stage of use of mechanical energy to return themineral particles to suspension, with the addition of dispersant afterthe filtration stage.

Thus, the filtering of suspensions not containing any dispersant isknown (Solid-liquid filtration and separation technology, A. Rushton, A.S. Ward, R. G. Holdich, 1996; Filtration: Equipment selection Modellingand process simulation, R. J. Wakeman, E. S. Tarleton, 1999; Practice offiltration, J. P. Duroudier, 1999), but the disadvantage is that cakeswhich are produced are difficult to re-disperse.

A process involving the introduction, into an aqueous suspension ofcalcium carbonate, of half the quantity of dispersant before filteringthe said suspension, and the addition of the other half after thefiltration stage, is also known (JP 53-025646) in order to obtain ahighly concentrated suspension of calcium carbonate.

Those skilled in the art are also familiar with another document (GB 1482 258) which reveals a process for the preparation of aqueoussuspensions of precipitated calcium carbonate (PCC) using a dispersantbefore the stage of concentration by a filtration in a single stage, butthis process has two major disadvantages.

The first consists of the need to use a pressure of over 17 bars to beable to filter and of the obligation to use very particular dispersivefacilities to disperse the cake obtained.

The second disadvantage of the said method lies in the fact that largequantities of dispersant are found in the filtrate, which generatesenvironmental and ecological problems, and industrial wastes treatmentproblems or problems of recirculation of the water used in the remainderof the process, and which also generates cost problems given the largequantities of dispersant used.

Similarly, patent GB 1 463 974 describes a method for filtration in asingle stage leading to the same disadvantages as those mentioned above.

Thus, the techniques known to those skilled in the art lead them to usethe dispersant agent either in full after the filtration, or half beforethe filtration stage and the other half after the filtration stage, oragain in using the dispersant agent before the filtration stage but withthe need to use firstly a large quantity of dispersant agent generatingthe abovementioned disadvantages, and secondly a very particulardispersive facility.

Generally, all these techniques known on today's date have thedisadvantage that they result in great difficulty in returning the caketo suspension if it is desired to obtain highly concentrated suspensionsof dry matter having a satisfactory rheology.

SUMMARY OF THE INVENTION

Thus, one of the aims of the invention is to offer a process forpreparing aqueous suspensions of loads and/or mineral pigments with asatisfactory rheology, i.e. to offer a process for preparing fluidaqueous suspensions of mineral matter, which are able to be pumped andable to be conveyed by the end user immediately after the filtrationstage, possibly followed by a compression, using small quantities ofdispersant, and allowing a check of the quantities of dispersant presentin the filtrate with a view to obtaining near-zero quantities ofdispersant present in the filtrate.

Near-zero quantities of dispersant present in the filtrate means thatthe end of the second stage corresponds to the appearance of thedispersant in the filtrate. This appearance of dispersant in thefiltrate is quantified by a measurement of electrical conductivity.

This process of preparing, as claimed in the invention, aqueoussuspensions of fluid mineral matter, able to be pumped and able to beconveyed by the end user immediately after the filtration stage, withsmall quantities of dispersant used, and allowing control of thequantities of dispersant present in the filtrate, is characterised bythe fact that it comprises a filtration in two separate stages, possiblyfollowed by a compression.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a diagram of the filtration process conducted in twostages.

DETAILED DESCRIPTION OF THE INVENTION

In a more particular manner, these two separate stages of filtrationconsist of a first stage in which a pre-layer is formed using nodispersant agent, followed by a second stage continuous with the firstin the presence of one or more dispersant agents, and in an even moreparticular manner followed by a second filtration stage containing 0.01%to 10%, preferentially 0.1% to 2% by dry weight of dispersant relativeto the dry weight of the mineral matter to be filtered.

When this pre-layer has been formed, the water of the pre-layer isreplaced, in the second stage, by the water of the second stagecontaining one or more dispersant agents such that the dispersant ordispersants are spread uniformly throughout the whole of the filtrationcake.

It should be noted that during the entire filtration period the pressureapplied has a value of around that commonly used in the traditionalfiltration processes. In an even more particular manner, this process asclaimed in the invention is characterised in that the quantity ofdispersant agent present in the filtrate is controlled and limited by acontinuous measurement of electrical conductivity of the filtrate and inthat the filtration stage is stopped as soon as the electricalconductivity of the filtrate increases. This stoppage of filtration atthe time when the electrical conductivity increases corresponds to anear-zero quantity of dispersant present in the filtrate.

Thus, the process as claimed in the invention enables aqueoussuspensions of fluid mineral matter to be obtained directly, which areable to be pumped and able to be conveyed immediately after thefiltration stage, possibly followed by a compression, using smallquantities of dispersant and with near-zero quantities of dispersantpresent in the filtrate.

To do so, the dispersant agent or agents used are chosen either from thedispersants commonly used in the field of suspension of mineral loadssuch as, for example, polyphosphates, polyacrylates, whetherfunctionalised or not, or any other polymer with a dispersant function,or from the anionic, cationic, non-ionic or zwitterionic surface activeagents.

The process of preparing aqueous suspensions of mineral matter asclaimed in the invention is characterised in that the mineral matter maybe chosen from natural calcium carbonate including notably the variouschalks, calcites or marbles, or chosen from the synthetic calciumcarbonates such as precipitated calcium carbonates at different stagesof crystallisation, or from the mixed magnesium and calcium carbonatessuch as dolomites, or from magnesium carbonate, zinc carbonate, lime,magnesia, barium sulphate such as barita, calcium sulphate, silica, themagnesio-silicates such as talc, wollastonite, clays and otheralumino-silicates such as kaolins, mica, metal or alkaline earth oxidesor hydroxides such as magnesium hydroxide, iron oxides, zinc oxides,titanium oxides, titanium dioxides in its anatase or rutile forms, andmixtures of them such as, notably, mixtures of talc and calciumcarbonate.

Preferentially, the mineral matter is chosen from natural calciumcarbonate, synthetic calcium carbonate also called precipitated calciumcarbonate, titanium dioxide in its anatase or rutile forms, kaolin,aluminium hydroxide, clays or their mixtures.

An additional aim of the invention is to develop an aqueous suspensionof mineral matter which is fluid, able to be pumped and conveyed by theend user immediately after the filtration stage, possibly followed by acompression.

This aqueous suspension of mineral matter as claimed in the invention ischaracterised in that it contains 0.01% to 10%, preferentially 0.1% to2% by dry weight of dispersant relative to the dry weight of mineralmatter to be filtered, and in that it is obtained by the process asclaimed in the invention.

In a more particular manner, it is characterised in that the mineralmatter may be chosen from among natural calcium carbonate, includingnotably the various chalks, calcites, marbles or again chosen from thesynthetic calcium carbonates such as precipitated calcium carbonates atdifferent stages of crystallisation, or again from the mixed carbonatesof magnesium and calcium such as the dolomites, or from magnesiumcarbonate, zinc carbonate, lime, magnesia, barium sulphate such asharita, calcium sulphate, silica, magnesio-silicates such as talc,wollastonite, clays and other alumino-silicates such as kaolins, mica,metal or alkaline-earth oxides or hydroxides such as magnesiumhydroxide, iron oxides, zinc oxides, titanium oxides, titanium dioxidesin its anatase or ruble loans, and mixtures of them such as, notably,mixtures of talc and calcium carbonate.

Finally, another aim of the invention concerns the use of aqueoussuspensions as claimed in the invention in the fields of paper, paint,water treatment such a notably the field of purification muds,detergency, ceramics, cements or hydraulic binders, public works, inksand varnishes, gluing of textiles or any type of industry requiring theuse of concentrated pigment suspensions, and concerns more particularlythe use of aqueous suspensions as claimed in the invention in the fieldsof paper, water treatment, paint and ceramics.

The scope and interest of the invention will be better perceived thanksto the following examples which cannot be restrictive.

EXAMPLE 1

This example illustrates the invention and concerns the filtration of anaqueous suspension of natural calcium carbonate and more particularly ofa Champagne chalk of median diameter 2 micrometers.

To accomplish this, 286.8 grams of the chalk suspension is used with adry matter concentration equal to 20.3% and, as filtration equipment, anitem of laboratory equipment of the company CHOQUENET consisting:

-   -   of a polypropylene frame with a chamber 2.2 cm wide and with a        section of 25 cm    -   of two steel plates, one of which fixed, with flutes on the        inner face, by which the filtrate is collected,    -   of two joints which provide sealing between the plates and the        frame,    -   of two polypropylene filtrating membranes from the company SEFAR        FYLTIS (ref.: F 0149 AN)

The filtration chamber (CF) can be supplied successively by a tank R1containing the suspension of the pigment to be concentrated, and then bya second tank R2 containing the same suspension as before, to which willbe added a quantity of dispersant Co required to obtain a concentratedcake (ES₂), and which can easily be removed, i.e. a cake with asufficient consistency to be removed from the filtration chamber in asingle element. Another alternative consists in R2 containing only adispersant solution.

The filtration process proper is conducted in two separate stages (seediagram 1):

-   -   1/during a first stage, a pre-layer from suspension 1 is formed        on the filtrating membranes,    -   2/followed by a second stage, in which filtration is undertaken        from suspension 2 containing the dispersant.

In the second stage, the water contained in the pre-layer is replaced bywater loaded with dispersant contained in suspension 2, such that at theend of the filtration stage the dispersant is spread uniformlythroughout the entire filtration cake.

Each of the filtration stages is undertaken under a 5 bar pressure.

The filtration stage is followed by a compression stage under a pressureof 15 bars, and enables a filtration cake of dryness ES₂ to be obtained.

The filtration cake is then subjected to a weak shearing to obtain asuspension also called fluid “slurry”.

This stage is undertaken using a standard laboratory mechanical agitatorof type RAYNERI filled with an adapted blade.

When the suspension is homogeneous, we measure its viscosity (visco 2)using a Brookfield^(T)′″ viscometer of the RVT type fitted with anadapted module.

The suspension as claimed in the invention, obtained by the process asclaimed in the invention described above and using 0.2% by dry weight,relative to the dry weight of dry chalk, of an ammonium polyacrylate ofmolecular weight by weight equal to 4,500 g/mole, is then an aqueoussuspension of chalk with a dry matter concentration of 76.8% and aBrookfield™ viscosity of 2,900 mPa·s measured at 10 revolutions perminute and of 518 mPa·s measured at 100 revolutions per minute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 170.6grams of filtrate. The content of dispersant in the filtrate is thennear-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the 40 end user immediately after the filtration stage.

After 8 days' storage of the suspension as claimed in the invention, anew measurement of Brookfield™ viscosity is taken after agitating theflask containing the said suspension. A Brookfield™ viscosity is thenobtained of 3,770 mPa·s measured at 10 revolutions per minute and of 645mPa·s measured at 100 revolutions per minute, showing that thesuspension obtained is fluid, and able to be pumped and conveyed, evenafter eight days' storage.

EXAMPLE 2

This example illustrates the invention and concerns the filtration of anaqueous suspension of natural calcium carbonate and more particularly ofa marble of median diameter of 0.75 micrometer.

To accomplish this, with the same operating method and the sameequipment as in example 1, firstly 173.2 grams of the aqueous suspensionof marble is used, the dry matter concentration of which is 27.6% andsecondly 0.5% by dry weight, relative to the dry weight of marble, of asodium polyacrylate called Coatex DV 834, to obtain directly an aqueoussuspension of marble the dry matter concentration of which is 72.1%, andthe Brookfield™ viscosity of which is 635 mPa·s measured at 10revolutions per minute and 240 mPa·s measured at 100 revolutions perminute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 114.5grams of filtrate. The dispersant content in the filtrate is near-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the end user immediately after the filtration stage.

After storage of 8 days of the suspension as claimed in the invention, anew Brookfield™ viscosity measurement is undertaken after agitating theflask containing the said suspension. A Brookfield″″ viscosity is thenobtained of 1,930 mPa·s measured at 10 revolutions per minute and of 550mPa·s measured at 100 revolutions per minute, showing that thesuspension obtained is fluid, and able to be pumped and conveyed, evenafter eight days' storage.

EXAMPLE 3

This example illustrates the invention and concerns the filtration of anaqueous suspension of precipitated calcium carbonate (PCC) of mediandiameter 0.9 micrometer.

To accomplish this, with the same operating method and the sameequipment as in example 1, firstly 156 grams of the aqueous suspensionof PCC is used, the dry matter concentration of which is 24% andmoreover 1.0% by dry weight, relative to the dry weight of PCC, of asodium polyacrylate of molecular weight by weight equal to 10,000g/mole, to obtain directly an aqueous suspension of PCC the dry matterconcentration of which is 65.9% and the Brookfield™ viscosity of whichis 4570 mPa·s measured at 10 revolutions per minute and 930 mPa·smeasured at 100 revolutions per minute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 123.7grams of filtrate. The dispersant content in the filtrate is thennear-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the end user immediately after the filtration stage.

EXAMPLE 4

This example illustrates the invention and concerns the filtration of anaqueous 15 suspension of natural calcium carbonate and more particularlyof a marble of median diameter 0.6 micrometer.

To accomplish this, with the same operating method and the sameequipment as in example 1, firstly 226.4 grams of the aqueous suspensionof marble is used, the dry matter concentration of which is 20.9%, andmoreover 1.0% by dry weight, relative to the dry weight of marble, of asodium polyacrylate called Coatex DV 834, to obtain directly an aqueoussuspension of marble the dry matter concentration of which is 70.0%, andthe Brookfield™ viscosity of which is 1,500 mPa·s measured at 10revolutions per minute and 670 mPa·s measured at 100 revolutions perminute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 177.7grams of filtrate. The content of dispersant in the filtrate is thennear-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the end user immediately after the filtration stage.

After 8 days' storage of the suspension as claimed in the invention, anew measurement of the Brookfield′ viscosity is taken after agitatingthe flask containing the said suspension. A Brookfield″″ viscosity isthen obtained of 1,840 mPa·s measured at 10 revolutions per minute andof 750 mPa·s measured at 100 revolutions per minute, showing that thesuspension obtained is fluid, and able to be pumped and conveyed, evenafter eight days' storage.

EXAMPLE 5

This example illustrates the invention and concerns the filtration of anaqueous suspension of titanium dioxide sold by the company Elementisunder the name RHD2.

To accomplish this, with the same operating method and the sameequipment as in example 1, firstly 390.9 grams of the aqueous suspensionof titanium dioxide is used, the dry matter concentration of which is24.2%, and moreover 0.3% by dry weight, relative to the dry weight oftitanium dioxide, of a copolymer sold by the company Coatex under thename Coatex BR3, to obtain directly an aqueous suspension of titaniumdioxide, the dry matter concentration of which is 74.2%, and theBrookfield™ viscosity of which is 1,100 mPa·s measured at 10 revolutionsper minute and 460 mPa·s measured at 100 revolutions per minute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 288.5grams of filtrate. The dispersant content in the filtrate is thennear-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the end user immediately after the filtration stage.

It is also advantageously used in the paint field.

EXAMPLE 6

This example illustrates the invention and concerns the filtration of anaqueous suspension of kaolin sold by the company Imerys under the nameSPS.

To accomplish this, with the same operating method and the sameequipment as in example 1 are used, firstly 229.1 grams of the aqueoussuspension of kaolin is used, the dry matter concentration of which is23.9%, and moreover 0.2% by dry weight, relative to the dry weight ofkaolin, of a sodium polyacrylate of molecular weight by weight equal to4,500 g/mole, to obtain directly an aqueous solution of kaolin the drymatter concentration of which is 68.0%, and the Brookfield™ viscosity ofwhich is 1,590 mPa·s measured at 10 revolutions per minute and 655 mPa·smeasured at 100 revolutions per minute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 167.7grams of filtrate. The dispersant content in the filtrate is thennear-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the end user immediately after the filtration stage.

EXAMPLE 7

This example illustrates the invention and concerns the filtration of anaqueous solution of aluminium hydroxide sold by the company Martinswerkunder the name 50L 104.

To accomplish this, with the same operating method and the sameequipment as in example 1, firstly 201.0 grams of the aqueous suspensionof aluminium hydroxide is used, the dry matter concentration of which is25.3%, and moreover 0.25% by dry weight, relative to the dry weight ofaluminium hydroxide, of a copolymer of molecular weight by weight equalto 3,500 g/mole, and consisting of acrylic acid and ofmethoxy-polyethylene glycol methacrylate of molecular weight 2,000,having been completely neutralised using soda, to obtain directly anaqueous suspension of aluminium hydroxide, the dry matter concentrationof which is 71.8%, and the Brookfield™ viscosity of which is 230 mPa·smeasured at 10 revolutions per minute and 230 mPa·s measured at 100revolutions per minute.

The filtration stage is stopped when the electrical conductivity of thefiltrate measured using an HI 8820N conductivity meter from HannaInstruments (Portugal) increases, i.e. after having collected 144.2grams of filtrate. The dispersant content in the filtrate is thennear-zero.

The suspension thus obtained is fluid, and able to be pumped andconveyed by the end user immediately after the filtration stage.

EXAMPLE 8

This example concerns the use of an aqueous solution of mineral load asclaimed in the invention in the paper field, and more particularlyconcerns the measurement of the optical properties of the suspension ofexample 4 obtained as claimed in the invention, and more particularlythe determination of the value of the capacity for diffusion of thevisible light of the aqueous suspension of example 4, together with theintrinsic brilliancy values of the pigment obtained by filtration.

This capacity for diffusion of visible light is expressed by a lightscattering factor S which is the Kubelka-Munk factor for diffusion oflight, determined by the method well known to those skilled in the artdescribed in the publications of Kubelka and Munk (Zeitschrift furTechnische Physik 12, 539, (1931)), of Kubelka (J. Optical Soc. Am.38(5), 448, (1948) and J. Optical Soc. Am. 44(4), 330, (1954)).

To accomplish this, a sheet of synthetic paper sold by the company ArjoWiggins Teape under the name Synteape is used.

Before being coated using a coating machine of the Hand Coater modelKC202 type, this sheet of paper of dimension 26 cm×18 cm, and ofspecific weight 60 to 65 g/m², is weighed and then subjected to a lightradiation of wavelength 457 nm on a black plate using an Elrepho™ 3000spectrophotometer from Datacolor (Switzerland) to determine thereflectance factor R_(b) of the uncoated paper on a black background.

The suspension for testing, formulated with a binder (12 partsstyrene-acrylic binder (Acronal S360D) for 100 g dry weight of mineralload for testing) is then applied on this pre-weighed paper sheet usinga coating machine of the Hand Coater model KC202 type.

The sheet of paper thus coated with different layer weights of between 5and 50 g/m² is then subjected to light radiation of wavelength 457 nmusing an Elrepho™ 3000 spectrophotometer from Datacolor (Switzerland) ona black plate to determine the reflectance factor of the paper on ablack background R_(o) and on a pile of at least 10 non-coated sheets ofpaper to determine the reflectance factor of the coated papers on awhite background R₁, where r is the reflectance factor of the pile ofuncoated sheets of paper.

The reflectance factor R_(sc) of the layer alone, on a black background,is then determined using the following formula:

$\begin{matrix}{R_{sc} = \frac{{R_{1} \cdot R_{b}}{R_{o} \cdot r}}{{\left( {R_{1} - R_{o}} \right) \cdot {rR}_{b}} + R_{b} - r}} & (1)\end{matrix}$

together with the transmission T_(sc) of the layer

$\begin{matrix}{T_{sc}^{2} = \frac{\left( {R_{o} - R_{sc}} \right)\left( {1 - {R_{sc}R_{b}}} \right)}{R_{b}}} & (2)\end{matrix}$

From these two quantities it is possible to calculate a theoreticalreflectance value R_(oo) for a layer of infinite thickness given by thefollowing formula:

$\begin{matrix}{\frac{1 - T_{sc}^{2} + R_{sc}^{2}}{R_{c}} = \frac{1 + R_{oo}^{2}}{R_{oo}}} & (3)\end{matrix}$

Thus, from this formula the light scattering factor S of the pigmentunder study may be calculated for each layer weight, given that, for alayer weight P,

$\begin{matrix}{{45{S.P.}} = {\frac{1}{b}\mspace{14mu} \coth^{- 1}\frac{\left( {1 - {aR}_{sc}} \right)}{{bR}_{sc}}}} \\{{{where}\mspace{14mu} a} = {0.5\left( {\frac{1}{R_{oo}} + R_{{oo})}} \right.}} \\{{{and}\mspace{14mu} b} = {0.5\left( {\frac{1}{R_{oo}} - R_{oo}} \right)}}\end{matrix}$

This light scattering factor S is traced according to the layer weightand the value S for a layer weight of 20 g/m² is determined byinterpolation.

In the present case the value S obtained is 157 m²/g and is entirelycomparable to the values obtained for suspensions of calcium carbonateof the prior art obtained according to the traditional means of thermalconcentration.

In addition, the 75° C. TAPPI brilliancy of the sheet of paperpreviously coated is determined before calendering by passing the coatedpaper into the Lehmann™ laboratory glossmeter. For paper coated usingthe coating color containing the aqueous suspension of calcium carbonateof example 4a 75° C. TAPPI brilliancy of 63.5 is obtained.

The coated paper is also calendered using a super-calendering machinewith 9 areas of contact between the two rollers, sold by Kleinewefers.

The 75° C. TAPPI brilliancy is then 69.3.

1-5. (canceled)
 6. An aqueous suspension of fluid mineral matter, which are able to be pumped and conveyed by the end user immediately after the filtration stage, possibly followed by a compression, characterised in that it contains 0.01% to 10%, preferentially 0.1% to 2% by dry weight of dispersant relative to the dry weight of mineral matter to be filtered, and in that it is obtained by the process as claimed in any of claims 1 to
 5. 7. An aqueous suspension of mineral matter as claimed in claim 6, characterised in that the mineral matter is chosen from among natural calcium carbonate such as the various chalks, calcites, marbles, or again chosen from the synthetic calcium carbonates such as the calcium carbonates precipitated at different stages of crystallisation, or from the mixed carbonates of magnesium and calcium such as the dolomites, or from magnesium carbonate, zinc carbonate, lime, magnesia, barium sulphate such as barita, calcium sulphate, silica, the magnesio-silicates such as talc, wollastonite, clays and other alumino-silicates such as the kaolins, mica, metal or alkaline-earth oxides or hydroxides such as magnesium hydroxide, iron oxides, zinc oxide, titanium oxide, titanium dioxides in the anatase or rutile forms, and mixtures of them, and moreover mixtures of talc and calcium carbonate.
 8. The aqueous suspension as claimed in claim 6 for use in the fields of paper, paint, water treatment, such as in the fields of purification muds, detergency, ceramics, cements or hydraulic binders, public works, inks and varnishes, gluing of textiles, and more particularly in the field of paper, ceramics, paint and water treatment. 